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94 xp 657x rotary valve clearance spec?

Got a rebuilt engine from guy on Craigslist that rebuilds them. Swapped over my exhaust manifold stator flywheel and rotary valve cover and intake he gave me a new rotary valve itself. So his instruction for break in were first 10 gallons premix while using the oil pump to then after that just gas don't have to mix oil pump will be the oil still. Ok so 10 gallons premixed 40:1 into the tank. Did the first step of breakin which were idle to 20% throttle for a half hr. Went out today to do the second part only going to 50% vary throttle for another half hr. So once in the water it fires right up let it idle for a minute or 2 and went to give it gas if I went more then 1/4 throttle it would bog out and die. So thought plugs were fouled swap them tweaked carb a little bit each way nothing really helped so I just putted around for a bit trying to see if it would clean. Which sadly it didn't back on the trailer and went home. Fires right up in the trailer how it does it the water but will rev great out of water. Just pulled the carbs a little bit ago to see it pop off was still in spec but I thought to myself I asked he guy if the species the rotary cover he said no but should all be in spec he milled the case or got milled and used my cover. Well just stuck a feeler gauge through intake and it's bigger then .022. This is deffinately out of spec am I right? Could this be my issue of bogging out and dying.

Re: 94 xp 657x rotary valve clearance spec?

Lean seizure is my guess. Can you pressurize your fuel system? Remove return gas line -- put small piece of hose from return nipple on back carb in a bottle. Pressurize with bicycle pump or pop off tester by pumping air into the return line. Check for leaks. May have gas tank inlet check valve leaking or leaking o -ring on gas filter. This will find it. You did replace the fuel lines and clean/replace the gas selector switch? Check your carbs again as well-- did you make sure the return gas orifice in both carbs are clear and open and passing gas. Pressure test will show this.

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Re: 94 xp 657x rotary valve clearance spec?

I already removed the carbs to double check everything and see if anything is out of place. Pop off pressure was 21 when I installed them, thinking of lowering to 18psi. Specs call for 16-21psi. I also have prok multifit filters on my carbs if that will effect anything stock everything else. Motors compression is 160-170 each cylinder great spark just about a inch little less. I changed all the fuel lines except for the vent lines which are black coast guard lines still. Every oil line basically did a complete in hull overhaul. Can I pressurize just the fuel tank to see if I have any leaks from there? And if so what psi should I pump to and how long should it hold for?

Re: 94 xp 657x rotary valve clearance spec?

Stock compression is around 150PSI.
Stock Flame Arrestors are restrictive, so when you change to aftermarket Flame Arrestors that have less restriction you will need to lower pop off pressure to get good throttle response. This may require several adjustments to get it right.

Re: 94 xp 657x rotary valve clearance spec?

Ok so compression of motor is on my pop off was at 21psi going to try and lower to 16 but read in manual it shouldn't go lower then 12. I'll let you know my outcome later on today thanks for your guys help